Flow line pig injector



Dec. 13, 1966 c. E. WAKEFIELD, JR 3,291,217

FLOW LINE PIG INJECTOR 2 Sheets-Sheet 1 Filed March 9, 1964 INVENTOR. 6HAR$ E. WAKEF/fdfi, J/Q

ATTURA/[y 13, 1966 c. E. WAKEFIELD, JR 3,291,217

FLOW LINE PIG INJECTOR 2 Sheets-Sheet 2 Filed March 9, 1964 INVENTOR.

United States Patent 3,291,217 FLOW LINE PIG INJECTOR Charles E. Wakefield, .Ir., Long Beach, Calif., assignor to Richtield Oil Corporation, Los Angeles, Calif., a corporation of California Filed Mar. 9, 1264, Ser. No. 350,208 4 Claims. (61. 166-75) My present invention relates to means for cleaning pipes internally, and more particularly relates to means for injecting a cleaning pig into a pipe to remove the accumulation of materials which tend to restrict the flow of fluids through the pipe line.

The accumulation of waxes, asphaltines, ice and scale in flow lines used to transport oil and gas from production wells tends to restrict flow through such lines. Various chemical, mechanical, and heating methods have been proposed for removing such deposits from the internal surfaces of such flow lines and other pipes, tubing, and the like. The present invention relates generally to the mechanical method for removing such deposits with a cleaning pig which is inserted into a pipe, flow line, pipe line, or the like and forced through the line by the fluid normally flowing therethrough to thereby clear the pipe of the aforementioned restrictions.

This invention in one of its more specific embodiments is concerned with providing a device for injecting a pig into a flow line at or near the well head of an under water oil well. The embodiment of my present invention described herein relates to offshore operations; however, my present invention may also be utilized for onshore oil and gas operations and for removing internal deposits in pipes and tubes generally.

The pig utilized in my present invention may be of any resilient material which is resistant to swelling upon contact with well fluids or moisture. Generally the shape of the pig should conform to the cross section or configuration of the flow line to be cleaned and preferably is either spherical or cylindrical.

The cleaning pigs have been manually injected into the flow lines; however, excessive labor is encountered in cleaning flow lines with manually injected pigs when the wells are widely separated or are remotely located such as in underwater Well sites. On the other hand, certain wells because of their inaccessibility have not previously been considered amenable to pig cleaning.

It is therefore an object of my present invention to provide an improved hydraulically operated apparatus for injecting a cleaning pig into a pipe.

It is also an object of my present invention to provide a remotely actuatable means for injecting a cleaning pig into a pipe with fluid pressure.

Other objects and a more complete understanding of my present invention may be had by reference to the following specification and the appended claims when taken in conjunction with the accompanying drawings, wherein:

FIG. 1 shows, in elevation the device of the present invention installed on a flow line at well head;

FIG. 2 is an enlarged cross-sectional elevation of the pig injector mechanism of my present invention;

FIG. 3 shows in cross-sectional elevation the pig injector mechanism with the fluid driven piston injecting a ma;

FIG. 4 is a sectional view taken on line 44 of FIG. 2

showing the injector barrel with the plunger mechanism therein;

FIG. 5 is a sectional view taken on line 55 showing the T.

With reference to the drawing generally, the pig injector of my present invention is installed on the flow line 12 near the production well head 14 so that cleaning pigs may be injected into the flow line through a T 16. A cleaning pig from the pig storage chamber 18 is injected with pig injector 10 into the flow line 12 where it is moved by the flow of well fluids through the flow line 12 to remove the accumulation of deposits therein.

Referring more particularly to the drawings, a pig injector mechanism 10 with suitable pig storage means 18 is attached to the flow line 12 with a suitable T 16 to facilitate the injection of pigs into the flow line. An injector body is attached to the flow line T through which cleaning pigs may be injected into flow line as will hereinafter be described. The storage chamber 18 is positioned on top of the injector body 40 at an opening 28 to permit pigs stored in storage chamber 18 to drop into the injector body 40. The storage chamber 18 is equipped with a coupling 19 which permits removal of the storage chamber 18 for access to the injector body 40 through the opening 28 therein. Pigs may be loaded into the storrage chamber 18 by first relieving the pressure in the chamber through bleed-oif valves 42 and and then removing the coupling 44 at the top of the storage chamber 18. The coupling 19, 44, and 46 may be of any readily releasable types such as a unibolt coupling. The lower surface 30 of the injector body may be removable with cap 31 which is removably connected to the injector body with coupling 46. Surface 30 bleeding off the pressure in the injector body through valve 50.

The pig is larger than the flow line 12 through which it is forced to thus be effective in dislodging accumulations in the line. The diameter of the T 16, however, is slightly larger than that of the pig 22 to facilitate injection of the pig into the flow line from the injector body 40. Spacer bar 80 is provided in the flow line T 16 through which the pig 22 passes into the flow line, to prevent plugging the flow line with the pig in the event of back flow.

An injector barrel 26 is connected to the injector body 40 and houses the injector mechanism used to drive a plunger 24 through the injector body to force a cleaning pig from the injector body into the flow line through T 16. The injector barred 26 is preferably formed in two parts as best viewed in FIG. 2, in order to separate the pressure in the plunger section 26b from the pressure in the cylinder section 26a. Plunger 24 is connected to the piston 32 which supplies the driving force for the plunger, through the rod 34 which is connected at one end to plunger 24 and at the other end to piston 32 as shown in FIG. 2. The injector barrel 26b and the injector body through which the plunger is driven are equipped with diametrically spaced guides 76 and 78 to center and guide the plunger 24 through the injector body. A packing gland 36 through which rod 34 is slideable, provides a seal between the plunger section 26b and the cylinder section 26a of the injector barrel 26. The rod 34 may be connected directly to the piston 32 although I prefer to use an enlarged rod section or a pipe member 54 with a rod socket 56 to make the rod 30 more rigid. The piston 32 has a packing plate 58 connected thereto with bolt 60 to hold packing 61 in the piston groove. A flange mem- J ber 62 is provided at the end of the injector barrel to which blind flange 63 is bolted to close off the barrel. Blind flange 63 has a port 64 therein for receiving hydraulic fluid through line 66.

A stop ring 52 is connected fixedly within the cylinder section 26a and a spring 38 biased between the stop ring 52 and the piston 32 as shown in FIG. 2.

Well head 14 may be any of the conventional type well heads with a tubing outlet 68 and a casing outlet 70, both of which may be equipped with hydraulically actuated safety valves 72 and 74, respectively. These safety valves may be of the type that are held open with hydraulic pressure applied through a hydraulic control line, permitting remote control of the valves. In one embodiment of my present invention the hydraulic control fluid used to hold the tubing and/or casing valves open is utilized to pressurize piston 32 in the injector barrel 26. In this embodiment, control fluid pressure manipulation actuates simultaneously both well head apparatus, such as a flow line control valve, and the pig ejector. Thus the control fluid line 20 is provided with a suitable T 21 so that hydraulic fluid can be supplied through line 66 to the injector barrel 26.

Although the apparatus shown in FIG. 1 is described in connection with a well head of the type described in my copending applications S.N. 100,411, filed April 16, 1961, it is apparent that the apparatus shown in FIG. 1 can be utilized with any well head where the tubing outlet is provided with a hydraulically controlled safety valve, or could be utilized without reference to the well head, on any type of line which it is desired to clean, by supplying hydraulic fluid to the injector barrel 26 to drive the piston 32.

During normal production, the piston 32 is driven to the right by fluid pressure exerted through the injector barrel hose 66, and the position of the plunger 24 is as shown in FIG. 3 with the plunger blocking the opening 28 in the injector body so that a cleaning pig cannot pass from the storage chamber 18 through opening 28 into the injector body 40. Thus fluid pressure is normally maintained on piston 32 to hold plunger 24 in the position shown in FIG. 3. Such pressure on the piston compresses the spring 38 between the piston 32 and the stop ring 52. When it is desired to inject a pig into the flow line, the fluid pressure exerted through hose 66 on piston 32 is released momentarily and the spring 38 drives piston 32 to the left to thereby retract the plunger 24 from opening 28 to the position shown in FIG. 2. Releasing the fluid pressure also closes the flow line control valve since it is operated conjointly with the pig ejector by using a common control fluid as shown in FIG. 1. With the plunger 24 in the retracted position shown in FIG. 2, a cleaning pig 22 drops from the storage chamber 18 through injector body opening 28 into the injector body 40 as shown in FIG. 2. When the pressure is again exerted against the piston 32 the plunger 24 is advanced to its normal operating position as shown in FIG. 3, and forces a pig into the flowline through T 16, at the same time reopening the flow line control valve 72.

Although my present invention has been described herein with a certain degree of particularity to set forth the best mode of operation of a specific embodiment thereof, the invention is not to be so limited, but should be given the full scope of the appended claims.

I claim:

1. Apparatus for injecting cleaning pigs into a flow line arranged to receive flow from an underwater well through a well head, said well head having a safety valve in the flow line adapted for actuation with a control fluid, comprising in combination:

an injector barrel in communication with said flow line,

a pig storage chamber having an opening through which a pig may be discharged from said storage chamber into said barrel,

a plunger positioned within said barrel,

a piston positioned within said barrel,

a rod operatively connected between said piston and said plunger so arranged that said piston drives said plunger in said barrel,

spring means for retracting said plunger to permit discharge of said pig from said storage chamber into said barrel through said opening,

a control fluid line in fluid communication with said safety valve and said piston,

said piston being movable in said barrel by said control fluid when said safety valve is actuated by said control fluid to drive said plunger past said opening thereby ejecting said pig from said barrel into said flow line with said plunger,

said piston moving means being arranged to compress said spring means so that when control fluid pressure is released said spring means retracts said plunger means.

2. Apparatus for injecting cleaning pigs into a flow line arranged to receive flow from an underwater well through a well head apparatus, said well head apparatus having a valve in the flow line adapted for actuation with a control fluid, comprising in combination:

an injector barrel in communication with said flow line,

said barrel having a cylinder section,

a pig storage chamber having an opening through which a pig may be discharged from said storage chamber into said barrel,

a piston positioned within said cylinder section,

plunger means operatively connected to said piston and so arranged that said piston drives said plunger means in said barrel toward said flow line,

a control fluid line in fluid communication with said valve and said cylinder section,

said piston being movable in said cylinder section by said control fluid when said valve is actuated by said control fluid to drive said plunger means past said opening thereby ejecting said pig from said barrel into said flow line with said plunger means, and

means for retracting said plunger means from said opening so that a pig may be discharged from said storage chamber into said barrel.

3. Apparatus for injecting cleaning pigs into a flow line arranged to receive flow from an underwater well through a well head, said well head having apparatus adapted for actuation with a control fluid, comprising in combination: an injector barrel in communication with said flow line, said barrel having a cylinder section and a plunger section,

a pig storage chamber having an opening through which a pig may be discharged from said storage chamber into said barrel in said plunger section, a piston positioned in said cylinder section, plunger means movable in said barrel plunger section and operatively connected to said piston and arranged to eject said pig discharged into said barrel from said storage chamber into said flow line,

means including a control fluid line in fluid communication with said well head apparatus and said cylinder section, for operating said piston with said control fluid to eject a pig into said flow line simultaneously with the actuation of said well head apparatus, and

means for retracting said plunger means from said opening so that a pig may be discharged from said storage chamber into said barrel.

4. Apparatus for injecting cleaning pigs into a flow line arranged to receive flow from an underwater well through a Well head apparatus, said well head apparatus having a valve in the flow line adapted for actuation with a control fluid, comprising in combination:

an injector barrel in communication with said flow line,

said barrel having a cylinder section,

a pig storage chamber having an opening through which a pig may be discharged from said storage References Cited by the Examiner chamber into said barrel, a piston positioned Within said cylinder section,

plunger means operatively connected to said piston and g g 13 Jones 2 so arranged that movement of said piston in said 5 553 5 2; g g cylinder section drives said plunger means in said barrel toward said flow line,

JACOB L. NACKENOFF, Primary Examiner. said piston belng moved by said control fluid to e ect a pig when said valve is actuated by said control CHARLES OCONNELL fluid. 10 J. A. LEPPINK, Assistant Examiner. 

3. APPARATUS FOR INJECTING CLEANING PIGS INTO A FLOW LINE ARRANGED TO RECEIVE FLOW FROM AN UNDERWATER WELL THROUGH A WELL HEAD, SAID WELL HEAD HAVING APPARATUS ADAPTED FOR ACTUATION WITH A CONTROL FLUID, COMPRISING IN COMBINATION: AN INJECTOR BARREL IN COMMUNICATION WITH SAID FLOW LINE, SAID BARREL HAVING A CYLINDER SECTION AND A PLUNGER SECTION, A PIG STORAGE CHAMBER HAVING AN OPENING THROUGH WHICH A PIG MAY BE DISCHARGED FROM SAID STORAGE CHAMBER INTO SAID BARREL IN SAID PLUNGER SECTION, A PISTON POSITIONED IN SAID CYLINDER SECTION, PLUNGER MEANS MOVABLE IN SAID BARREL PLUNGER SECTION AND OPERATIVELY CONNECTED TO SAID PISTON AND ARRANGED TO EJECT SAID PIG DISCHARGED INTO SAID BARREL FROM SAID STORAGE CHAMBER INTO SAID FLOW LINE, MEANS INCLUDING A CONTROL FLUID LINE IN FLUID COMMUNICATION WITH SAID WELL HEAD APPARATUS AND SAID CYLINDER SECTION, FOR OPERATING SAID PISTON WITH SAID CONTROL FLUID TO EJECT A PIG INTO SAID FLOW LINE SIMULTANEOUSLY WITH THE ACTUATION OF SAID WELL MEANS APPARATUS, AND MEANS FOR RETRACTING SAID PLUNGER MEANS FOR SAID OPENING SO THAT A PIG MAY BE DISCHARGED FOR SAID STORAGE CHAMBER INTO SAID BARREL. 